The task of collecting cyclic data (such as menstrual periods) from research study participants is fraught with many problems including large amounts of missing and incorrect data, high paper storage and handling expenses, illegible responses, participant fatigue, and respondent dropout. The proposed ProCycle is an electronic menstrual calendar designed for small, hand-held computers known as personal digital assistants (PDAs). ProCycle will allow a woman to record menstrual and other symptom data directly into the PDA, download the data via modem to a study site or clinic, and have the results easily and quickly read by a health care provider or researcher. ProCycle will address problems of traditional paper methods by validating responses immediately; eliminating data transcription errors; minimizing data cleaning activities; presenting help and reminders to participants; and monitoring the times that data are entered. ProCycle is expected to improve the quality of the data, increase production, and reduce the costs of research studies. In Phase I, we will design and develop software specifications for the tool; develop a prototype; do a pilot evaluation of the prototype, and produce a detailed project plan for implementation. In Phase II, we will implement the actual product and do a full-scale evaluation. PROPOSED COMMERCIAL APPLICATION ProCycle can be used whenever collection of daily symptomatic occurrences are required. The possible markets for ProCycle include universities, government agencies, the pharaceutical industry and the over 500 managed care insurers. Fertility studies are a primary application. The American Society for Reproductive Medicine lists over 11,000 practitioners specializing in fertility.